Question

I’m missing something here and I know it’s not that hard but I’m not getting it. I have a plist of dictionaries. It’s being loaded into a mutable array which then populates my tableView.

plist sample:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
    <dict>
        <key>title</key>
        <string>entry1</string>
        <key>checkedState</key>
        <string>NO</string>
    </dict>
    <dict>
        <key>title</key>
        <string>accessoriesImage</string>
        <key>checkedState</key>
        <string>NO</string>
    </dict>
    <dict>
        <key>title</key>
        <string>activationCharge</string>
        <key>checkedState</key>
        <string>NO</string>
    </dict>

And I’m trying to access those dictionary values but I’m getting confused.

Here’s my initialization:

static NSString *kTitleKey = @"title";
static NSString *kCheckedState = @"checkState";

@interface ViewController ()

@end

@implementation ViewController

@synthesize attributesTableView, attributesArray;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nil bundle:nil];
    if (self) {
        NSString *attributesFile = [[NSBundle mainBundle] pathForResource:@"attributesPlist"ofType:@"plist"];

        attributesArray = [[NSMutableArray alloc] initWithContentsOfFile:attributesFile];

    }
    return self;
}

Skipping to the relevant bits, I’m populating my tableView cells with:

cell.textLabel.text = [[attributesArray objectAtIndex:[indexPath row]] valueForKey:kTitleKey];

Later in didSelectRowAtIndexPath I’m trying to check those dictionary values and that’s where I’m failing.

Example:

if ([[attributesArray valueForKey:kTitleKey = @"All"] valueForKey:kCheckedState = @"YES"]) {
                        [attributesArray setValue:kCheckedState = @"NO" forKey:@"All"];

[attributesArray setValue:kCheckedState = @"YES" forKey:[[attributesArray objectAtIndex:[indexPath row]] valueForKey:kTitleKey]];

I’m getting this error: valueForUndefinedKey:]: this class is not key value coding-compliant for the key YES.’

I know I’m just accessing it wrong but I’m not sure how I do that when I’m using a mutable array filled with mutable dictionaries.

Answer 1

I think your syntax for setting values is off. In the last code snippet you posted, you have this:

[attributesArray valueForKey:kTitleKey = @"All"]

Contrary to what you might think, this doesn’t set the title to “All”; instead, it replaces the value of kTitleKey with the string “All”, then fetches the value of “All” from the attributes array. Instead, I think you want something like:

[attributesArray setValue:@"All" forKey:kTitleKey]

You’ll have to make similar updates throughout that last example. Remember the critical distinction here:

• valueForKey: gets a value. You can never set something using valueForKey:, even if you throw some equals signs in.
• setValue:forKey: sets a value. You’ll want to use this whenever you need to change attributesArray.

You might want to read up on key-value coding for more information.